The enthalpy change when a sample of solid benzene ( C ₆ H ₆ ) completely melts at its melting point is 39.6 kJ . If the molar enthalpy of fusion of benzene is 9.9 kJ mol ⁻¹ , the mass of the benzene sample melted is ________ g .

Step-by-step solution

Molar mass of benzene ( C ₆ H ₆ ) = 6 12 + 6 1 = 78 g mol ⁻¹ Number of moles of benzene melted, n = Total enthalpy change Molar enthalpy of fusion n = 39.6 kJ 9.9 kJ mol ⁻¹ = 4 moles Mass of benzene = n Molar mass = 4 mol 78 g mol ⁻¹ = 312 g Answer: 312